Swift-无法对齐具有不同字体大小的堆栈元素答案

【问题标题】：Swift- unable to align stack elements with different font sizesSwift-无法对齐具有不同字体大小的堆栈元素
【发布时间】：2020-09-09 21:00:42
【问题描述】：

我有 2 个 UILabel 如下：

private lazy var titleLabel: UILabel = {
    let label = UILabel()
    label.textColor = Constants.mainFontColor.withAlphaComponent(0.7)
    label.translatesAutoresizingMaskIntoConstraints = false
    label.isUserInteractionEnabled = false
    label.sizeToFit()
    return label
}()

private lazy var valueLabel: UILabel = {
    let label = UILabel()
    label.textColor = Constants.mainFontColor
    label.translatesAutoresizingMaskIntoConstraints = false
    label.isUserInteractionEnabled = false
    label.sizeToFit()
    return label
}()

然后将这些标签放入 UIStackView：

private lazy var stackView: UIStackView = {
    let stack = UIStackView(arrangedSubviews: [titleLabel, valueLabel])
    stack.translatesAutoresizingMaskIntoConstraints = false
    stack.axis = .horizontal
    stack.spacing = 5
    stack.alignment = .firstBaseline
    addSubview(stack)
    return stack
}()

然后我创建了几个实例，例如：

private lazy var flightNumber: FuelSheetHeaderField = {
    return FuelSheetHeaderField(title: FuelSheetStringsField.flightNumber.title.localized,
                                value: viewModel.flightNumber, titleFontSize: 17, valueFontSize: 24)
}()

然后将它们放入单独的堆栈视图中：

   private lazy var flightData: UIStackView = {
        let stack = UIStackView(arrangedSubviews: [flightNumber, aircraftReg, dateTime, origin])
        stack.axis = .horizontal
        stack.distribution = .equalSpacing
        stack.spacing = Constants.standardHorizontalStackSpacing
        return stack
    }()

标题标签的字体大小为 12，值的字体大小为 17。除了一个自定义为相应的字体大小为 17 和 2 的标签。我试图让所有元素沿着同一基线对齐。我添加了以下约束：

titleLabel.firstBaselineAnchor.constraint(equalTo: valueLabel.firstBaselineAnchor),

但是效果如下：

大多数堆栈元素都是对齐的，但您可以看到第一个字体较大的元素比第二个元素高。这让我有点发疯。如何修复它，使堆栈中的所有元素沿同一基线对齐。

【问题讨论】：

标签： swift uiview uistackview

【解决方案1】：

我认为您在尝试跨堆栈视图使用基线时会遇到麻烦。

一个选项 - 不确定它是否适合你 - 是将所有标签放在一个水平堆栈视图中，并使用 .setCustomSpacing() 调整标签之间的空间。

举个例子：

和Debug -> View Debugging -> Show View Frames:

这是我用来生成的代码：

class AlignedStackViewController: UIViewController {

    let detailsStack: UIStackView = {
        let v = UIStackView()
        v.axis = .vertical
        v.alignment = .leading
        v.distribution = .fill
        v.spacing = 12
        return v
    }()
    
    let dataStack: UIStackView = {
        let v = UIStackView()
        v.axis = .horizontal
        v.alignment = .firstBaseline
        v.distribution = .fill
        v.spacing = 5
        return v
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = UIColor(red: 0.928, green: 0.973, blue: 1.0, alpha: 1.0)

        let fdLabel = UILabel()
        fdLabel.text = "FLIGHT DETAILS"
        
        detailsStack.addArrangedSubview(fdLabel)
        detailsStack.addArrangedSubview(dataStack)
        
        detailsStack.translatesAutoresizingMaskIntoConstraints = false
        
        view.addSubview(detailsStack)
        
        // respect safe area
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            // position stack view at 40, 100
            detailsStack.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
            detailsStack.topAnchor.constraint(equalTo: g.topAnchor, constant: 100.0),
        ])
        
        addLabelPair(with: "#", value: "VS0105", titleFontSize: 17, valueFontSize: 24)
        addLabelPair(with: "Reg:", value: "GAAAA", titleFontSize: 12, valueFontSize: 17)
        addLabelPair(with: "Departure:", value: "09 Sep 2020", titleFontSize: 12, valueFontSize: 17)
        addLabelPair(with: "at", value: "08:34", titleFontSize: 12, valueFontSize: 17)

        updateStackSpacing()

    }
    
    func updateStackSpacing() -> Void {
        // make sure stack has been filled
        guard dataStack.arrangedSubviews.count == 8 else {
            return
        }
        // verbose for clarity
        let flightNumberLabel = dataStack.arrangedSubviews[1]
        let aircraftRegLabel = dataStack.arrangedSubviews[3]
        dataStack.setCustomSpacing(12, after: flightNumberLabel)
        dataStack.setCustomSpacing(12, after: aircraftRegLabel)
    }
    
    func addLabelPair(with title: String, value: String, titleFontSize: CGFloat, valueFontSize: CGFloat) -> Void {
        
        let tLabel = UILabel()
        let vLabel = UILabel()
        
        tLabel.font = UIFont.systemFont(ofSize: titleFontSize)
        vLabel.font = UIFont.systemFont(ofSize: valueFontSize)
        
        tLabel.textColor = UIColor.black.withAlphaComponent(0.7)
        vLabel.textColor = UIColor.black

        tLabel.text = title
        vLabel.text = value
        
        dataStack.addArrangedSubview(tLabel)
        dataStack.addArrangedSubview(vLabel)
        
    }

}

【讨论】：

【解决方案2】：

我认为，uiLabel 似乎有默认填充

而默认的填充值取决于字体大小。

尽管sizeToFit，结果是一样的

【讨论】：